Polaritonic Fiber Probe and Method for Nanoscale Measurements

ABSTRACT

The invention offers high resolution and accuracy for nanoscale device characterization from ultraviolet through microwave wavelengths. Instead of collecting light after emission in near-field that decays to far-field, the present invention directly couples the near-field waves to a polaritonic-coated probe. The polaritonic coating can be formed on an wavelength tuned optical fiber to receive the coupled emission and form polaritons, including plasmons, phonons, and magnons, using the polaritonic material. The polaritons propagate along the probe decay back into the fiber core without substantial losses to far-field and are transmitted to a detector, such as a spectroscope. The coupling of the near-field energy to emission detected through the tip apex of fiber can be expressed as emission spectra. Through mapping with other spatial points, multi-dimensional displays and other information can be provided. The resolution can be less than 100 nanometers, including an order of magnitude less than 100 nanometers.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.16/886,169, filed May 28, 2020, which claims the benefit of U.S.Provisional Ser. No. 62/854,855, filed May 30, 2019, and is incorporatedfully herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION Field of the Invention

The disclosure relates generally to equipment and related method formeasuring temperatures of objects and surfaces. More specifically, thedisclosure relates to equipment and related method for measuring andmapping temperatures of an object or surface with nanoscale resolution.

Description of the Related Art

The desire to measure temperatures of objects and surfaces withmicroscopic resolution, such as with sub-micron resolution, hasincreased over the last few decades. Some efforts have been made toincrease resolution but fall short of the resolution desired.

FIG. 1 is a schematic diagram of a known proposed system for measuringsurface temperature with an IR detector. For example, Roodenko, Y.,Ephrat, P., Naglia, L., and Katzir, A., Collection-mode near-fieldscanning infrared microscope based on silver halide probes, Appl. Phys.Lett. 85, 5538 (2004), (https://doi.org/10.1063/1.1830674) discloses “acollection-mode scanning near-field microscope [SNIM] for themidinfrared spectral range, employing probes fabricated from taperedsilver halide fibers. The system was tested in the photon scanningtunneling regime, where a sample was illuminated under total internalreflection conditions.” Abstract. The system uses a laser beam toilluminate a sample under total internal reflection conditions (TIR) atan angle to a vertical datum. A tip of a tapered silver halide fiber hasan end facet that can receive near-field IR radiation to pass into thefiber and measures the tunneling power at a distance h from the sample.The end facet needs to be large to receive sufficient energy, but smallto have resolution. The competing interests results in a balance thatlacks sufficient resolution for current needs.

FIG. 2A is a schematic diagram of another known proposed system formeasuring surface temperature with a tip. FIG. 2B is a micro opticalphoto of an object to measure the surface temperature with the system inFIG. 2A. FIG. 2C is a micro atomic force image of the object in FIG. 2Bto measure the surface temperature with the system in FIG. 2A. FIG. 2Dis a micro scanning thermal radiation image of the object in FIG. 2Bmeasured with the system in FIG. 2A. Another example is by De Wilde, Y.,Formanek, F., Carminati, R., Thermal radiation scanning tunnellingmicroscopy. Nature 444, 740-743 (2006).(https://doi.org/10.1038/nature05265). The article states that“[near-field scanning optical microscopy] NSOM is well suited to studysurface waves such as surface plasmons or surface-phonon polaritons.Using an aperture NSOM with visible laser illumination, a near-fieldinterference pattern around a corral structure has been observed, whosefeatures were similar to the scanning tunnelling microscope image of theelectronic waves in a quantum corral.” Abstract. The article “describesan infrared NSOM that operates without any external illumination: it isa near-field analogue of a night-vision camera, making use of thethermal infrared evanescent fields emitted by the surface, and behavesas an optical scanning tunnelling microscope.” Id. In general, it isunderstood that near-field radiation is scattered by the atomic forcemicroscope (AFM) tip. The tip acts as a scattering center that radiatesin the far field a signal linearly related to the infrared evanescentfields emitted by the surface. The scattered near-field signal isdifferentiated from a constant far-field signal by a lock-in filteringtied to the tapping frequency of the AFM tip. The boundary between agold disk and a substrate is resolved with 100 nm resolution. The systemand method lack the desired resolution and sensitivity for accuracy.

FIG. 3A is a schematic diagram of another known proposed system with aheated AFM near-field scattering setup for measuring surfacetemperature. FIG. 3B is a set of results in photo form and graph formfrom the setup shown in FIG. 3A. A third example of prior efforts is byJones, A, Raschke, M, Thermal Infrared Near-Field Spectroscopy. NanoLett. 2012, 12, 1475-1481 (2012) (https://doi.org/10.1021/n1204201g).The article states, “Despite the seminal contributions of Kirchhoff andPlanck describing far-field thermal emission, fundamentally distinctspectral characteristics of the electromagnetic thermal near-field havebeen predicted. However, due to their evanescent nature, their directexperimental characterization has remained elusive. Combining scatteringscanning near-field optical microscopy with Fourier-transformspectroscopy using a heated atomic force microscope tip as both a localthermal source and scattering probe, we spectroscopically characterizethe thermal near-field in the mid-infrared. We observe the spectrallydistinct and orders of magnitude enhanced resonant spectral near-fieldenergy density associated with vibrational, phonon, and phonon-polaritonmodes. We describe this behavior and the associated distinct on- andoff-resonance nanoscale field localization with model calculations ofthe near-field electromagnetic local density of states.” Abstract. It isunderstood that heated AFM tip or sample generates thermal evanescentfields. The evanescent fields are scattered by the AFM tip intodetectable far-field radiation. The scattered near-field spectrum iscollected by a Michelson interferometer detected using an HgCdTephotodiode. The scattered near-field signal is differentiated fromconstant far-field signal by lock-in filtering tied to the tappingfrequency of the AFM tip with a 50 nm spatial resolution. The evanescentthermal near-field signal relates to spectral energy density associatedwith the EM-LDOS and contains information about phonon-polariton,phonon, and vibrational resonances. Here, too, the system and methodlack the desired resolution and sensitivity for accuracy.

FIG. 4 is a schematic graph of a known near-field heat transfer betweenobjects based on distance between the objects. It is believed that atleast one reason for the inadequate resolution and sensitivity is thevery small distance that the radiant thermal energy exponentiallydissipates from the surface, that is, within only a few hundrednanometers. According to St-Gelais, R., Zhu, L., Fan, S. et al.,Near-field radiative heat transfer between parallel structures in thedeep subwavelength regime. Nature Nanotech 11, 515-519 (2016)(https://doi.org/10.1038/nnano.2016.20), near-field energy is containedjust a few hundred nm from the surface and decays exponentially.

FIG. 5A is a schematic diagram showing evanescent near-field wavespropagating along a surface before decay. Evanescent EM waves decays ashort distance from the surface, no photons emit into space. Thedirection of energy propagation is often along the surface.

FIG. 5B is a schematic diagram showing far-field waves propagating intospace. Far-field waves emit photons that propagate into space, carryingenergy far away from the surface.

FIG. 6A is a schematic diagram of near-field, far-field, and veryfar-field waves on or from the surface. FIG. 6B is a combination ofgraphs from spectra of the near-field, far-field, and very far-fieldwaves of FIG. 6A. The X-axis of the graphs indicates the angularfrequency in radians per second (w, 10¹² s⁻¹). The resonant frequency inthe bottom panel at 178.7×10¹² s⁻¹ is equal to 10.54 micrometers inwavelength. The Y-axis indicates the intensity of spectra based onfrequency and position above the surface (I (w, z_(c))). The top graphis being very far-field at about 1000 um from the surface, the middlegraph being far-field at about 2 um from the surface, and the bottomgraph being near-field at about 0.1 um from the surface. Near-fieldradiation is scattered and radiates into far-field regions, carryingenergy far away from the surface. Thus, the near-field IR landscape of asurface is far different from the far field landscape related to asurface.

FIG. 9A is a schematic top view of a known microwave co-planar waveprobe. FIG. 9B is a photo of an embodiment of the probe with a PCBconnection. FIG. 9C is a schematic of the co-planar wave probe formed asa funneling resonator. FIG. 9D is a schematic chart of power spectraldensity relative to frequencies for the resonator of FIG. 9C. Inaddition to IR measurements noted above, similar principles of far-fieldmeasurement availability and higher resolution near-field emissionmeasurements apply to other wavelengths, including ultraviolet (“UV”) tomicrowave wavelengths. For example, in FIG. 9A and FIG. 9B, a microwaveco-planer wave (“CPW”) probe can provide near-field nano sizedmicrowaves at its tip 40. The probe can be made into a CPW microwaveresonator 38 that funnels the microwaves through an output path 42.Far-field measurements shown in FIG. 9D at the output path 42 show thepower density at different frequencies. However, such measurements donot measure the power density at the near field microwave production ofthe tip 40 on a nano-scale. It would be beneficial to be able to measurenear-field emission with the resulting higher resolution.

FIG. 10A is a known scanning electron microscope image of an opticalfiber probe for ultraviolet frequencies. FIG. 10B is a mapping result ofaluminum gallium nitrogen quantum well structure using the UV fiberprobe of FIG. 10A with a lateral resolution exceeding 150 nanometers.FIG. 10C is a schematic chart of spectral density relative tofrequencies from the UV fiber probe measurements of the quantum wellstructure. It would be beneficial to be able to measure higherresolution.

FIG. 11A is a schematic of a known experimental setup for laser pulsethrough a split-hole resonator. FIG. 11B is a scanning electronmicroscope image of the split-hole resonator of FIG. 11A. FIG. 11C is achart of spectra of a second and third harmonics generated by theresonator. A split-hole resonator (“SHR”) 46 is formed from a nanorod 48and a nanohole 50 in a metal nanofilm 52 and generally produces highefficiency of third-harmonics generation and multiphoton luminescence. Ashort laser pulse 54 is used to excite the SHR 46 and the far-fieldemission can be measured. It would be beneficial to be able to measurenear-field emission with the resulting higher resolution.

While the issues have been identified of the rapid scattering from thesurface of evanescent near-field waves and consequential loss, those inthe art have attempted to capture the near-field data accurately, thesystem and methods have eluded those in the field with the level ofresolution desired for the needed advancement of the science. Thereremains a need for a solution that can measure with increased resolutionand sensitivity that gathers more of the near-field energy whileminimizing losses into far-field space.

BRIEF SUMMARY OF THE INVENTION

The invention offers high resolution and accuracy for nanoscale devicecharacterization from ultraviolet through microwave wavelengths. Insteadof collecting light after emission in near-field that decays tofar-field, the present invention directly couples the near-field wavesto a polaritonic-material coated probe. The polaritonic coating can beformed on an wavelength tuned optical fiber to receive the coupledemission and form polaritons, including plasmons, phonons, and magnons,using the polaritonic material. The polaritons propagate along the probedecay back into the fiber core without substantial losses to far-fieldand are transmitted to a detector, such as a spectroscope. The couplingof the near-field energy to emission detected through the tip apex offiber can be expressed as emission spectra. Through mapping with otherspatial points, multi-dimensional displays and other information can beprovided. The resolution can be less than 100 nanometers, including atleast an order of magnitude less than 100 nanometers.

The disclosure provides a system for measuring an object having asurface, comprising: a probe formed of an optical fiber configured toconduct frequency emission from the object comprising: a portion of theoptical fiber forming a tip; a polaritonic coating on the optical fibertip configured to receive near-field energy from the surface and formpolaritons responsive to the radiation that propagate along thepolaritonic coating; and wherein the fiber is configured to allow thepolaritons to decay into the fiber and transmit emission from thedecayed polaritons along the fiber.

The disclosure further provides a method of measuring an object,comprising: placing a probe and the object having near-field energyadjacent each other, the probe having a polaritonic coating configuredto receive the near-field energy; allowing the near-field energy to formpolaritons on the polaritonic coating; allowing the polaritons topropagate along the polaritonic coating; allowing the polaritons todecay and emit energy into the fiber; conducting the emitted energyalong the fiber; and detecting the energy in the fiber from the decayedpolaritons.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 is a schematic diagram of a known proposed system for measuringsurface temperature with an IR detector.

FIG. 2A is a schematic diagram of another known proposed system formeasuring surface temperature with a tip.

FIG. 2B is a micro optical photo of an object to measure the surfacetemperature with the system in FIG. 2A.

FIG. 2C is a micro atomic force image of the object in FIG. 2B tomeasure the surface temperature with the system in FIG. 2A.

FIG. 2D is a micro scanning thermal radiation image of the object inFIG. 2B measured with the system in FIG. 2A.

FIG. 3A is a schematic diagram of another known proposed system with aheated AFM near-field scattering setup for measuring surfacetemperature.

FIG. 3B is a set of results in photo form and graph form from the setupshown in FIG. 3A.

FIG. 4 is a schematic graph of a known near-field heat transfer lossbetween objects based on distance between the objects.

FIG. 5A is a schematic diagram showing evanescent near-field wavespropagating along a surface before decay.

FIG. 5B is a schematic diagram showing far-field waves propagating intospace.

FIG. 6A is a schematic diagram of near-field, far-field, and veryfar-field waves on or from the surface.

FIG. 6B is a combination of graphs from spectra of the near-field,far-field, and very far-field waves of FIG. 6A.

FIG. 7A is a schematic diagram of an illustrative embodiment of aninfrared polaritonic fiber probe system capable of nanoscale temperaturemapping according to the invention.

FIG. 7B is an enlarged schematic view of the fiber probe adjacent thesurface to be measured of FIG. 7A.

FIG. 8 is a graph of simulated emission collection of energy from asurface by a silver coated polaritonic fiber compared to a thermalradiation scanning tunneling microscope.

FIG. 9A is a schematic top view of a known microwave co-planar waveprobe.

FIG. 9B is a photo of an embodiment of the probe with a PCB connection.

FIG. 9C is a schematic of the co-planar wave probe formed as a funnelingresonator.

FIG. 9D is a schematic chart of power spectral density relative tofrequencies for the resonator of FIG. 9C.

FIG. 10A is a known scanning electron microscope image of an opticalfiber probe for ultraviolet frequencies.

FIG. 10B is a mapping result of aluminum gallium nitrogen quantum wellstructure using the UV fiber probe of FIG. 10A with a lateral resolutionexceeding 150 nanometers.

FIG. 10C is a schematic chart of spectral density relative tofrequencies from the UV fiber probe measurements of the quantum wellstructure.

FIG. 11A is a schematic of a known experimental setup for laser pulsethrough a split-hole resonator.

FIG. 11B is a scanning electron microscope image of the split-holeresonator of FIG. 11A.

FIG. 11C is a chart of spectra of a second and third harmonics generatedby the resonator.

FIG. 12A is a schematic diagram of another illustrative embodiment of apolaritonic fiber probe system capable of nanoscale characterizationsaccording to the invention.

FIG. 12B is a representative display from a detector of a near-fieldenergy results for a wavelength range of UV to visible light.

FIG. 12C is a representative display from a detector of a near-fieldenergy results for a wavelength range of visible light through infrared.

FIG. 12D is a representative display from a detector of a near-fieldenergy results for a wavelength range encompassing microwave.

FIG. 13A is a schematic of the co-planar wave probe as an enlargedschematic view of previously described FIG. 9A.

FIG. 13B is a scanning electron microscope image of aNormal-Insulator-Superconductor junction of the center conductor of FIG.13A.

FIG. 14 is a schematic diagram of another illustrative embodiment of apolaritonic fiber probe system capable of nanoscale characterizationsaccording to the invention.

DETAILED DESCRIPTION

The Figures described above and the written description of specificstructures and functions below are not presented to limit the scope ofwhat Applicant has invented or the scope of the appended claims. Rather,the Figures and written description are provided to teach any personskilled in the art how to make and use the inventions for which patentprotection is sought. Those skilled in the art will appreciate that notall features of a commercial embodiment of the inventions are describedor shown for the sake of clarity and understanding. Persons of skill inthis art will also appreciate that the development of an actualcommercial embodiment incorporating aspects of the present disclosurewill require numerous implementation-specific decisions to achieve thedeveloper's ultimate goal for the commercial embodiment. Suchimplementation-specific decisions may include, and likely are notlimited to, compliance with system-related, business-related,government-related, and other constraints, which may vary by specificimplementation, location, or with time. While a developer's effortsmight be complex and time-consuming in an absolute sense, such effortswould be, nevertheless, a routine undertaking for those of ordinaryskill in this art having benefit of this disclosure. It must beunderstood that the inventions disclosed and taught herein aresusceptible to numerous and various modifications and alternative forms.The use of a singular term, such as, but not limited to, “a,” is notintended as limiting of the number of items. Further, the variousmethods and embodiments of the system can be included in combinationwith each other to produce variations of the disclosed methods andembodiments. Discussion of singular elements can include plural elementsand vice-versa. References to at least one item may include one or moreitems. Also, various aspects of the embodiments could be used inconjunction with each other to accomplish the understood goals of thedisclosure. Unless the context requires otherwise, the term “comprise”or variations such as “comprises” or “comprising,” should be understoodto imply the inclusion of at least the stated element or step or groupof elements or steps or equivalents thereof, and not the exclusion of agreater numerical quantity or any other element or step or group ofelements or steps or equivalents thereof. The device or system may beused in a number of directions and orientations. The terms “top”, “up’,“upward’, “bottom”, “down”, “downwardly”, and like directional terms areused to indicate the direction relative to the figures and theirillustrated orientation and are not absolute relative to a fixed datumsuch as the earth in commercial use. The term “coupled,” “coupling,”“coupler,” and like terms are used broadly herein and may include anymethod or device for securing, binding, bonding, fastening, attaching,joining, inserting therein, forming thereon or therein, communicating,or otherwise associating, for example, mechanically, magnetically,electrically, chemically, operably, directly or indirectly withintermediate elements, one or more pieces of members together and mayfurther include without limitation integrally forming one functionalmember with another in a unitary fashion. The coupling may occur in anydirection, including rotationally. The term “inner,” “inward,”“internal” or like terms refers to a direction facing toward a centerportion of an assembly or component, such as longitudinal centerline ofthe assembly or component, and the term “outer,” “outward,” “external”or like terms refers to a direction facing away from the center portionof an assembly or component. The order of steps can occur in a varietyof sequences unless otherwise specifically limited. The various stepsdescribed herein can be combined with other steps, interlineated withthe stated steps, and/or split into multiple steps. Similarly, elementshave been described functionally and can be embodied as separatecomponents or can be combined into components having multiple functions.Some elements are nominated by a device name for simplicity and would beunderstood to include a system of related components that are known tothose with ordinary skill in the art and may not be specificallydescribed. Various examples are provided in the description and figuresthat perform various functions and are non-limiting in shape, size,description, but serve as illustrative structures that can be varied aswould be known to one with ordinary skill in the art given the teachingscontained herein. As such, the use of the term “exemplary” is theadjective form of the noun “example” and likewise refers to anillustrative structure, and not necessarily a preferred embodiment.Element numbers with suffix letters, such as “A”, “B”, and so forth, areto designate different elements within a group of like elements having asimilar structure or function, and corresponding element numbers withoutthe letters are to generally refer to one or more of the like elements.Any element numbers in the claims that correspond to elements disclosedin the application are illustrative and not exclusive, as severalembodiments may be disclosed that use various element numbers for likeelements.

The invention offers high resolution and accuracy for nanoscale devicecharacterization from ultraviolet through microwave wavelengths. Insteadof collecting light after emission in near-field that decays tofar-field, the present invention directly couples the near-field wavesto a polaritonic-coated probe. The polaritonic coating can be formed onan wavelength tuned optical fiber to receive the coupled emission andform polaritons, including plasmons, phonons, and magnons, using thepolaritonic material. The polaritons propagate along the probe decayback into the fiber core without substantial losses to far-field and aretransmitted to a detector, such as a spectroscope. The coupling of thenear-field energy to emission detected through the tip apex of fiber canbe expressed as emission spectra. Through mapping with other spatialpoints, multi-dimensional displays and other information can beprovided. The resolution can be less than 100 nanometers, including atleast an order of magnitude less than 100 nanometers.

Because the coating is directly on the fiber, the probe can be used inmultiple environments, such as liquid, gas, and it is believed even invivo for nanoscale measurements. Further, the concepts of thepolaritonic-coated tip can be integrated into a variety of scanningprobe microscopes, including atomic force microscopes (“AFM”), scanningtunneling microscopes (“STM”), near-field scanning optical microscopes(“NSOM”), and others. The invention can be used for nanoscale chemicalsensing, temperature sensing, microwave device performancecharacterization, magnetic imaging, and other foreseeable andunforeseeable purposes. By detecting the near-field signal withoutsubstantially emitting to the far-field, the invention is able toacquire previously lost information about nanoscale dynamics.

FIG. 7A is a schematic diagram of an illustrative embodiment of aninfrared polaritonic fiber probe system capable of nanoscale temperaturemapping according to the invention. FIG. 7B is an enlarged schematicview of the fiber probe adjacent the surface to be measured of FIG. 7A.The system 2 includes an optical fiber 4, specifically, in at least oneembodiment, an IR-tuned optical fiber (“IR fiber”). IR fiber is fiberthat is made with material that has low optical absorption and hightransmission in the IR range, for example, fluoride, chalcogenide andsilver halide. For example and without limitation, an IR fiber could beturned for mid-IR frequencies of about 2-10 micrometers.

In at least one example of an embodiment, the system can include ascanning tunneling microscope system. The IR fiber can be coupled to anactuator 6 to control probe spacing from the sample and other movement.For example and without limitation, an actuator 6 can include a piezotube that can expand and contract based on applied electrical energythat can be coupled with a power supply 8 that can establish a tunnelingcurrent with a bias voltage to a ground 10 on the sample. The tunnelingcurrent can be used to control the distance of the tip 14 (such as thetip apex 16) from the sample. The tip can be formed of various sizes andoptimized for the application. For more precise measurements, the tipapex can be controlled to within 1 nm of the sample. Other actuators arecontemplated. Equipment such as controllers, sensors, and so forth forthe system 2 are not shown but would be known to those with ordinaryskill in the art. The spatial resolution of measurements can be lessthan 100 nm, less than 50 nm, less than 10 nm, less than 5 nm, and lessthan 1 nm, and anywhere in between.

The tip 14 can include an fiber core 18 that can be coated with apolaritonic coating 20 to receive the near-field energy 22 from thesample 12. For example and without limitation, the polaritonic coating20 can be formed of a metal such as gold or silver, aluminum zinc oxide(“AZO”), indium tin oxide (“ITO”), other transparent conducting oxides(“TCO”) (doped or not doped), vanadium oxide as a transparentcarrier-selective material, and other suitable materials that can formpolaritons for the system. Once received on the tip, the near-fieldenergy forms polaritons 24 that propagate along the polaritonic coating.For purposes herein, the term “polaritons” include plasmons, phonons,magnons, and other relevant polaritons. The polaritonic coating can beresponsive to polaritons at different frequencies depending on the typeof polariton. As the polaritons decay along the polaritonic coating, theenergy is transferred into the fiber core 18 as emission energy 26 fortransmission to a detector 30, such as a spectrometer in spectroscopy.Output can include, without limitation, a spectra line graph, an x-ygraph of a two-dimensional surface of the object, or an x-y-z graph of athree-dimensional surface including depth and height of the object, andother outputs as may be suitable for the application.

FIG. 8 is a graph of simulated emission collection of energy from asurface by a silver coated polaritonic fiber compared to a thermalradiation scanning tunneling microscope. A polaritonic IR fiber probewith silver thin film of about 40 nm according to the invention wassimulated for near-field thermal emission collection from a sample. Theresults were compared with a conventional thermal radiation scanningtunneling microscope. The top line in the graph shows the collectionefficiency of the polaritonic IR fiber probe. The bottom line shows thecollection efficiency of the objective lens of the known thermalradiation scanning tunneling microscope in the far-field. The efficiencyis closest at about a wavelength of 1.8 um. At higher wavelengths, theefficiency diverges significantly where at a wavelength of 4.0 um, theefficiency of the polaritonic IR fiber probe is about an order ofmagnitude higher than the thermal radiation scanning tunnelingmicroscope in the far-field.

While the above discussion has focused on infrared radiation, otherfrequency radiative energy can be also measured to yield differentcharacteristics of a material. The wavelengths can vary across a widerange, generally from ultraviolet through microwave. The examples belowillustrate a general embodiment adaptable for multiple frequencies and aspecific microwave embodiment.

FIG. 12A is a schematic diagram of another illustrative embodiment of apolaritonic fiber probe system capable of nanoscale characterizationsaccording to the invention. Similar to the description of the system inFIG. 7A, the optical fiber 4 can be coupled to a position sensor 28 thatprovides input to a surface detection feedback controller 32. Thecontroller 32 can control movement of the optical fiber and the distanceof the tip 14 (such as the tip apex 16) from the sample 12. For moreprecise measurements, the tip apex can be controlled to within 1 nm ofthe sample. Other actuators are contemplated. Other equipment such asother controllers, sensors, and so forth for the system 2 are not shownbut would be known to those with ordinary skill in the art. The spatialresolution of measurements can be less than 100 nm, less than 50 nm,less than 10 nm, less than 5 nm, and less than 1 nm, and anywhere inbetween.

The tip 14 can include the fiber core 18 that can be coated with anpolaritonic coating 20 to receive near-field energy 22 from the sample12. Once received on the tip, the near-field energy forms polaritons 24that propagate along the polaritonic coating. For purposes herein, theterm “polaritons” include quasiparticles that support a surface wave,including but not limited to plasmons, phonons, magnons, and otherrelevant polaritons. The polaritonic coating 20 can be selected basedthe wavelength or range of wavelengths being detected. As the polaritons24 decay along the polaritonic coating 20, the resulting energy istransferred into the fiber core 18 as emission energy 26 fortransmission to a detector 30, such as a spectrometer in spectroscopy.Output can include, without limitation, a spectra line graph, an x-ygraph of a two-dimensional surface of the object, or an x-y-z graph of athree-dimensional surface including depth and height of the object, andother outputs as may be suitable for the application.

FIG. 12B is a representative display from a detector of a near-fieldenergy results for a wavelength range of UV to visible light. FIG. 12Cis a representative display from a detector of a near-field energyresults for a wavelength range of visible light through infrared. FIG.12D is a representative display from a detector of a near-field energyresults for a wavelength range encompassing microwave. Some polaritoniccoatings are more appropriate for certain wavelengths or ranges ofwavelengths. One or more coatings can be appropriate for one or moreranges or specific wavelengths while other one or more coatings can beappropriate or one or more other ranges or other specific wavelengths. Afactor in determining appropriateness is whether the wavelength of thenear-field energy (generally producing polaritons) will cause aresonance with the polaritonic coating to exchange energy and excite thepolaritons for movement. For example and without limitation, thepolaritonic coating 20 can be formed of a metal such as gold or silver,aluminum zinc oxide (“AZO”), indium tin oxide (“ITO”), other transparentconducting oxides (“TCO”) (doped or not doped), vanadium oxide as atransparent carrier-selective material, and other suitable materialsthat can form polaritons for the system. It is understood that otherranges, portions of ranges, expanded ranges and specific ranges orspecific wavelengths in one or more the ranges can be selected fornear-field energy analysis and the above examples noted in FIGS. 12B-12Dand the examples of material for the polaritonic coatings are onlyillustrative. As one of many examples, the embodiment can have aresolution of one or two (or more) orders of magnitude compared to priorart such as shown in FIGS. 10A-10C regarding UV to visible light nearfield-energy.

FIG. 13A is a schematic of the co-planar wave probe as an enlargedschematic view of previously described FIG. 9A. FIG. 13B is a scanningelectron microscope image of a Normal-Insulator-Superconductor junctionof the center conductor of FIG. 13A. As one of many examples, theinvention can be used for measure the near-field energy from the NISjunction on a small nano-scale level.

FIG. 14 is a schematic diagram of another illustrative embodiment of apolaritonic fiber probe system capable of nanoscale characterizationsaccording to the invention. This embodiment reflects the embodiments andaspects described relative to FIG. 7A and FIG. 12A. However, the tip 14can be configured particularly for microwave polaritons as plasmons ormagnons. Generally, the tip 14 can include the fiber core 18 that can becoated with a polaritonic coating 20 to receive near-field energy 22from the sample 12. The polaritonic coating 20 can be formed as astructured surface to efficiently support polaritons along the surface.Slits 34 formed in the coating 20 can form the structured surfacecoating. The slits 34 can have a width W that is smaller than thewavelength of the near-field energy being coupled with the polaritoniccoating 20.

Once received on the tip, the near-field energy forms polaritons 24 thatcan propagate along the polaritonic coating 20. As the polaritons 24decay along the polaritonic coating 20, the resulting energy istransferred into the fiber core 18 as emission energy 26 fortransmission to a detector 30, such as a spectrometer in spectroscopy.Output can include, without limitation, a spectra line graph, an x-ygraph of a two-dimensional surface of the object, or an x-y-z graph of athree-dimensional surface including depth and height of the object, andother outputs as may be suitable for the application.

Other and further embodiments utilizing one or more aspects of theinventions described above can be devised without departing from thedisclosed invention as defined in the claims. For example, differentstructures, diameters, shapes, angles, wavelengths, coatings, material,and other parameters provided in this application can vary and arelimited only by the scope of the claims.

The invention has been described in the context of one or moreembodiments, and not every embodiment of the invention has beendescribed. Obvious modifications and alterations to the describedembodiments are available to those of ordinary skill in the art. Thedisclosed and undisclosed embodiments are not intended to limit orrestrict the scope or applicability of the invention conceived of by theApplicant, but rather, in conformity with the patent laws, Applicantintends to protect fully all such modifications and improvements thatcome within the scope of the following claims.

1. A system for measuring an object having a surface, comprising: aprobe formed of an optical fiber configured to conduct emission from theobject comprising: a portion of the optical fiber forming a tip; apolaritonic coating on the optical fiber tip configured to receivenear-field energy from the surface and form polaritons responsive to theradiation that propagate along the polaritonic coating; and wherein thefiber is configured to allow the polaritons to decay into the fiber andtransmit emission from the decayed polaritons along the fiber.
 2. Thesystem of claim 1, wherein the near-field energy is directly coupledinto the polaritons on the polaritonic coating.
 3. The system of claim1, further comprising a detector configured to detect emissions from thepolaritons.
 4. The system of claim 1, further comprising an actuatorcoupled to the probe and configured to move the probe in relation to anenergy between the actuator and the object surface.
 5. The system ofclaim 1, wherein a spatial resolution of the probe is at least less than100 nm.
 6. A method of measuring an object, comprising: placing a probeand the object having near-field energy adjacent each other, the probehaving a polaritonic coating configured to receive the near-fieldenergy; allowing the near-field energy to form polaritons on thepolaritonic coating; allowing the polaritons to propagate along thepolaritonic coating; allowing the polaritons to decay and emit energyinto the fiber; conducting the emitted energy along the fiber; anddetecting the energy in the fiber from the decayed polaritons.
 7. Themethod of claim 6, further comprising directly coupling the near-fieldenergy into polaritons on the polaritonic coating.
 8. The method ofclaim 6, further comprising controlling a distance between a tip of theprobe and the object surface with a tunneling current.
 9. The method ofclaim 6, wherein detecting the energy comprises generating an emissionspectral display.
 10. The method of claim 6, wherein detecting theenergy in the fiber from the decayed polaritons comprises detecting atless than 100 nm spatial resolution.